OK, I've spent the past hour and a half searching the web with no luck:(

I was using Octoprinter to control my Lulzbot TAZ5, but since Octoprinter doesn't support Cura 3.2.21, I'm now direct-connecting to the printer.
When I load the stl file Cura correctly displays the envelope dimensions, however when the parts print, they are stretched in the X direction by about 25%.

Any ideas on how to correct this - short of manually scaling the model in the X direction to "fool" the slicer?

Think I am missing something here. I use Cura 3.4.1 (and have used 3.2.1 in the past) to connect to Octoprint with no problem. Are you using Octoprint to do the slicing? If so, that is using a very old CuraEngine (prior to Ultimaker taking over development). Recommend just slicing on PC and sending the gcode to Octoprint.

I've given-up using Octoprint and am now direct USB connecting to Lulzbot TAZ5 - this is where the problem of stretching occurs: BTW it is "Y" not "X" (got my directions mixed-up)

The "Propare" tab selected, the envelope size is correct, and the part "looks" correct (ie. no stretching in the view port). This is what leads me to believe that the Y-stretching is happening in the gcode.